<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
        <button id="start">开始</button>
        <button id="end">结束</button>
        <h1 id="txt">开始抽奖吧</h1>
        <script>
            var tag=document.getElementById('txt');
            var start=document.getElementById('start');
            var end=document.getElementById('end');
        var timer;          
            
            var list=['老李','老王','老张','老笑','老孙','老陈','老相','老老'];
            console.log(list[0]);
            console.log(list.length);
            start.onclick=function(){
                clearInterval(timer);
                timer=setInterval(function(){
                    tag.innerHTML=parseInt(Math.random()*10);
                },100)
            }

            end.onclick=function(){
                clearInterval(timer);
            }
        </script>
</body>
</html>